Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

This work presents microstrip and Substrate Integrated Waveguide (SIW) based monopulse comparators (MC) working at two different frequency bands for automated target detection. Center frequencies of the comparators are 3.5 GHz and 28 GHz with their operating bands fall in the sub-6 GHz and millimeter wave frequency range. Planar microstrip line based design is adopted for making the comparator at lower band. Simulation result shows simulated impedance matching of > 14.4 dB at the input ports over 3.4-3.6 GHz. The maximum phase deviation at the sum port of the comparator is 2.2°. At the millimeter wave range of 27.75-28.25 GHz, comparators are designed for working in a single plane and dual plane configuration. SIW is used to design these two comparators at millimeter wave. Single plane MC shows average differential phases at its sum and difference ports are -1.34° and 176.58°, respectively, with a minimum simulated return loss of > 16.26 dB at the input ports. The maximum simulated phase deviation at the sum port of dual plane SIW MC is 13.8° with impedance matching > 15.5 dB for the input ports of the comparator. © 2020 IEEE.

Department of Electrical Engineering

World University root node

Proceedings of the 2020 International Symposium on Antennas and Propagation, APSYM 2020

Microstrip and SIW based Monopulse Comparators for Microwave and Millimeter Wave Applications

This work presents a broadband polarization insensitive circuit analog absorber from X to Ka-band applications. It consists of two different circular rings loaded with lumped resistors on two sides of the TLY-5 substrate, and the whole structure is terminated with the perfect electric conductor (PEC) through an air-spacer. It demonstrates 90% absorption bandwidth over 18.44 GHz with 116.8% fractional bandwidth. The proposed meta-surface is polarization insensitive due to the four-fold (circular) symmetry architecture, and it shows good angular stability for both TE and TM oblique incidences within the acceptable limit. The transmission line based equivalent circuit model shows near agreement with full-wave analysis. The novelty of this design lies in the usage of both sides of the substrate made this structure compact with a periodicity of 0.207\lambda and thickness 0.09\lambda, where \lambda is the free-space wavelength corresponding to the lowest frequency of the absorption band. Results from electromagnetic simulator prove the ability of proposed absorber in applications like electromagnetic shielding and energy harvesting. © 2020 IEEE.

Asia-Pacific Microwave Conference Proceedings, APMC

Design of Compact, Broadband Polarization Insensitive Dual-Circular Circuit Analog Absorber for X, Ku and Ka-Band Applications

This paper presents Substrate Integrated Waveguide (SIW) based beam scanning antenna array utilizing a Butler Matrix (BM). The proposed beamforming network is designed utilizing Electromagnetically coupled (EMC) four elements antenna array. BM has the feature of optimal amplitude and phase imbalance at its output ports. The four-beam array demonstrates wide scanning range from -42° to +42° with a peak gain of 11.1 dBi and peak side lobe levels (SLLs) of -10.12 dB over the frequency of 27.75-28.25 GHz for 5G cellular communication applications. © 2020 IEEE.

SIW Butler Matrix Driven Beam Scanning Array for Millimeter Wave 5G Communication

This work furnishes an Ultra-Wideband (UWB) Antipodal Vivaldi Antenna (AVA) utilizing a systematic approach. Initially, conventional AVA is designed for reference, and then periodic slit edges or corrugations are done at the edges of the AVA to get the desired frequency range of operation with increased gain. Moreover, periodic slots are done on the modified flares of the AVA to obtain the desired frequency range over a wider bandwidth (1.9 - 14 GHz). Finally, a tooth shaped dielectric director, with a higher dielectric constant is attached to the substrate to further improve the gain and directivity of the modified AVA. The proposed structure demonstrates a simulated gain of of 11.2 dBi, which is an improvement of 2.2 dBi over its non-dielectric counterpart. © 2020 IEEE.

High Gain Elliptically Tapered Antipodal Vivaldi Antenna with Tooth Shaped Dielectric Lens

In this paper, a reflective type wideband polarization converter is proposed. It can convert both linear to linear and linear to circular for different frequency bands. It consists of a simple dual-cut circular split ring resonator, printed on a thin FR-4 dielectric substrate terminated with the ground. Simulation result shows, an x/y polarized incident wave conversion to y/x reflected wave in three bands (4.49-4.63 GHz, 7.11-10.75 GHz, 14.94-16.93 GHz) and x/y polarized incident wave returns the circularly polarized reflected wave in three different bands (4.86-5 GHz, 6.09-6.46 GHz, 11.83-14.03 GHz). The proposed structure is compact with the unit-cell periodicity of 0.14λ and overall thickness 0.047λ, where λ corresponds to the lowest frequency of the operational band. The performance of the proposed structure is investigated under different oblique incidences. Surface current patterns are studied to analyze the reason behind the wideband response. Authors strongly believe that the proposed structure has the potential to be used in different applications where both linear-cross and linear-circular conversion are the primary concerns. © 2020 IEEE.

IEMTRONICS 2020 - International IOT, Electronics and Mechatronics Conference, Proceedings

Wideband dual-cut circular ring based linear-cross and linear-circular polarizing reflector

A common way to analyze electrostatic microelectromechanical systems (MEMS) actuators is to use their energy-displacement landscape. Here, we describe an alternative approach to analyze electrostatic MEMS actuators using their energy-charge landscape. This technique involves coordinate transformation from displacement to charge, thereby formulating the Hamiltonian of electrostatic MEMS actuators in terms of charge. We investigate the use of the energy-charge landscape to analyze static pull-in, dynamic pull-in, and pull-out phenomena. The voltage expressions derived using this method are identical with those derived using the conventional energy-displacement landscape. In addition, we also obtain the expressions for charge under static and dynamic pull-in conditions. This work can aid in the design and analysis of electrostatic MEMS devices. As a case study, the analysis of a feedback capacitor-MEMS actuator system is presented to illustrate the application of the energy-charge landscape. © 1963-2012 IEEE.

Fulltext

IEEE Transactions on Electron Devices

Analysis of Electrostatic MEMS Using Energy-Charge Landscape

Ultrasound medical imaging systems typically follow standard delay and sum (DAS) beamforming at the reception for image reconstruction. In DAS, the echo signals that are returned to the transducer are aligned in time and summed to form the beamformed signal. To improve the image quality and the signal to noise ratio of DAS, a non-linear beamforming named delay multiply and sum (DMAS) has been proposed in the literature, where, the signals arriving at the transducer are aligned in time and are pairwise multiplied in all possible combinations before summation. This provides better coherence, a correlation-based data-driven apodization, and consequently result in better contrast and resolution. However, the computational complexity of DMAS is higher than DAS thus restricting its real-time implementation. This paper presents two novel VLSI architectures for the implementation of DMAS, whose complexity is independent of the number of transducer elements. The proposed architectures are implemented on xc7z010c1g400-1 FPGA and the results clearly show the channel independency of the proposed architectures. © 2020 IEEE.

SPCOM 2020 - International Conference on Signal Processing and Communications

VLSI architectures for Delay Multiply and Sum Beamforming in Ultrasound Medical Imaging

Musculoskeletal (MSK) ultrasound imaging aims to provide pictures of tissues and bones such as muscles, tendons, ligaments, joints and soft tissues throughout the body. One of the major landmarks in MSK ultrasound are the bones, and segmentation of bone surface has numerous applications in computer-aided orthopedic diagnosis. In this work, a novel method of bone aware image enhancement of MSK ultrasound images is presented. A combination of fundamental and harmonic US images is used for bone segmentation. The method for bone segmentation takes into account the acoustic characteristics of the intensity of bones used for computing their acoustic shadows, local phase-based features such as local energy, local phase, and feature symmetry based on a reported work in literature. It is combined with integrated backscattering of the bone to provide a probability map of the bone. Bone location in probability map was found based on the centroid of the intensity distribution. Further, image enhancement of the extracted region of interest based on the bone for distinctive visualization of the muscular and tendon region above the bone structure is presented. The image enhancement techniques employed are gamma correction, histogram equalization, adaptive histogram equalization and an improved frequency based super-resolution of ultrasound images. © 2020 IEEE.

IEEE Region 10 Annual International Conference, Proceedings/TENCON

Towards bone aware image enhancement in musculoskeletal ultrasound imaging

The Path Cover and Cycle Cover problems are well-known generalizations of the classical Hamiltonian Path and Hamiltonian Cycle problems. Here, we are given an undirected graph on n vertices and a positive integer r and the task is to check if there are r vertex-disjoint paths (cycles) that together visit all the vertices of the graph exactly once. Path Cover and Cycle Cover remain NP-hard even when restricted to chordal graphs (Information Processing Letters 1986) but are polynomial-time solvable on proper interval graphs (Discrete Mathematics 1993 and Proceedings of WADS 2019). In this paper, we study the complexity of Path Cover and Cycle Cover with respect to a structural parameter, namely, distance to proper interval graphs. In particular, we show that Path Cover and Cycle Cover are fixed-parameter tractable (FPT) when parameterized by k, the size of a proper interval deletion set (a set of vertices whose deletion results in a proper interval graph). For this purpose, we design an algorithm with O(2O ( k log k )nO ( 1 )) running time for each of these problems. Our algorithms use several interesting properties of proper interval graphs and a dynamic programming procedure over clique partitions to solve these problems in the mentioned time. As a consequence, we get the same fixed-parameter tractability results for Hamiltonian Cycle and Hamiltonian Path problems with the same parameterization. Recently, Chaplick et al. (Proceedings of WADS 2019) obtained polynomial kernels and compression algorithms for Path Cover and Cycle Cover parameterized by a different measure of similarity with proper interval graphs. Our FPT algorithms also adds to this study of structural parameterizations for these classical problems. © 2020, Springer Nature Switzerland AG.

Department of Computer Science and Engineering

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

Graph Hamiltonicity Parameterized by Proper Interval Deletion Set

This article studies the efficacy of the Metropolis algorithm for the minimum-weight codeword problem. The input is a linear code C given by its generator matrix and our task is to compute a nonzero codeword in the code C of least weight. In particular, we study the Metropolis algorithm on two possible search spaces for the problem: 1) the codeword space and 2) the generator space. The former is the space of all codewords of the input code and is the most natural one to use and hence has been used in previous work on this problem. The latter is the space of all generator matrices of the input code and is studied for the first time in this article. In this article, we show that for an appropriately chosen temperature parameter the Metropolis algorithm mixes rapidly when either of the search spaces mentioned above are used. Experimentally, we demonstrate that the Metropolis algorithm performs favorably when compared to previous attempts. When using the generator space, the Metropolis algorithm is able to outperform the previous algorithms in most of the cases. We have also provided both theoretical and experimental justification to show why the generator space is a worthwhile search space to use for this problem. © 1997-2012 IEEE.